Mike,
nas (you know what that is) on a Windows Home Server (WHS) - I have an old-ish HP server running WHS version 1. This has software which duplicates the data on the hard drives but this does not negate the need for a back up of your data. Preferably the back up of your data should be held somewhere off site, and you NEED a back up, regardless of whatever server operating system or software you use. There is a newer version of WHS (2011) but I believe Microsoft will be dropping the Windows Home server concept.
Edit - you don't NEED WHS but it is quite a convenient way of managing server storage.
JRiver is software used to access and play music, I like it and for me it is more intuitive than iTunes, your mileage may vary. It costs approx $30 / £20 and there are other options around such as Foobar.
External DACs - there are many and the prices vary from very cheap to very expensive and you need to audition. You've probably seen quite a few DAC threads here.
A coax for your cdx is so that you can use the digital output coax of the cdx to bypass the internal dac in the cdx and pass the digital signal into the external dac that you have auditioned and bought in the previous point. Assuming, that is, that the internal dac in the cdx is of lower quality than what the external dac can produce.
My River is an app for iphone, ipad etc for controlling JRiver. For android use Gizmo as the controlling app.
It can all work together seamlessly, and once you have a streaming set up you will love the convenience and quality. But, whatever you do, please make sure you back up the data - ripping CDs is a lengthly process if you have any number of them and you don't want to have to do it twice.
